Adhesiveless fiber optic connector, and an apparatus and method for terminating a fiber optic cable to an adhesiveless fiber optic connector

ABSTRACT

An adhesiveless fiber optic connector includes a collet mechanism having cable gripping fingers for initially gripping a fiber buffer upon movement of the collet into a body of the connector, and which is subsequently secured within the connector by crimping, includes keying tabs which cooperate with slots in the main body of the connector for retaining the collet within the connector prior to termination, and for preventing rotation of the collet during termination, the keying tabs being pushed out of the slots during termination to adhere to the main body of the connector following crimping. An apparatus for facilitating termination of a fiber optic cable to such an adhesiveless connector includes a transport mechanism to which the fiber buffer is clipped, and a guiding mechanism in the form of separable jaws for the exposed fiber, as well as a crimp mechanism and fiber cutting and polishing apparatus. The apparatus can be used to carry out a method involving the steps of preparing the fiber cable for termination, capturing a bare fiber in a guiding mechanism, securing the fiber buffer to a transporting mechanism, and transporting the cable so that the cable is guided by the guiding mechanism into the collet, after which the transporting mechanism is used to push the collet into the connector and force keys of the collet out of their slots and grip the fiber buffer.

This application is a Division of nonprovisional application Ser. No.08/801,142 filed Feb. 18, 1997, Pat. No. 5,862,289

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of fiber optics, and in particularto an adhesiveless fiber optic connector, an apparatus for facilitatingtermination of a fiber optic cable to an adhesiveless fiber opticconnector, and a method of terminating a fiber optic cable to anadhesiveless fiber optic connector.

2. Discussion of Related Art

Light energy generated by a broadband source and modulated to carryinformation is commonly transmitted by fiber optic systems using fiberoptic cables and connectors. Typically, a fiber optic system begins witha source such as a laser which generates a light energy signal andinjects it into an optical fiber. The signal travels through the systemvia a series of optical fibers which are connected in end-to-end fashionby connection assemblies. Each connection assembly is made up of a fiberoptic connector attached to or terminated to the end of an opticalfiber, and an adapter which receives the ends of the connectors andprecisely aligns the optical fibers in the connectors in abutting,end-to-end relationship.

In order to minimize attenuation of the signal as it passes from theoptical fiber in one connector to an optical fiber in the adjoiningconnector, it is imperative that the optical fibers in the connectors bepositioned so that they are precisely aligned when the connectors areconnected to one another via the adapter. In view of external forces andenvironmental stresses which are applied to the connectors it isnecessary to securely fix the optical fiber within the connector so asto avoid drift or displacement which results in misalignment of theoptical fiber when connected in a connection assembly.

A variety of techniques have been proposed to secure an optical fiber ofa fiber optic cable within an optical fiber connector. One common methodis to inject an adhesive, such as an epoxy, into the connector to fillthe space between the optical fiber and the inner surface of theconnector. When the adhesive is cured, the optical fiber is heldsecurely in position within the connector.

While adhesives provide good retention of the optical fiber within theconnector, they suffer from the disadvantages of being difficult toapply with precision and of requiring time to cure before the opticalfiber is held securely. These disadvantages are especially serious forapplications where the cable cannot be removed from an installation andin situ termination of the cable to a new connector is necessary.

To avoid the use of adhesives, U.S. Pat. No. 5,088,804, the disclosureof which is hereby incorporated by reference, describes an optical fiberconnector which utilizes a deformable, elastomeric material placedwithin the connector to surround the optical fiber. When the connectoris assembled with an optical fiber, the elastomeric material iscompressed inwardly around the optical fiber to secure it in position.

Alternatively, U.S. Pat. No. 4,812,006, the disclosure of which ishereby incorporated by reference, discloses an adhesiveless retentionmechanism for an optical fiber cable connector which utilizes acompressible collet which, when fully inserted in the connector, iscompressed inwardly and clamps against the outside of the fiber opticcable.

In addition, U.S. Pat. No. 5,140,662, the disclosure of which is herebyincorporated by reference, discloses an adhesiveless retentionarrangement in which the main body of the connector is crimped directlyto the cable, eliminating any sort of collet or separate retentionarrangement.

While effectively eliminating the need for adhesives, the elastomericretention and collet retention techniques of the type described in theabove-cited patents, as well as other known techniques for securingoptical fiber within connectors without the need for adhesives, have anumber of disadvantages. These disadvantages generally include decreasedstability relative to adhesive-based arrangements, and/or relativecomplexity. Even where adequate resistance to drift is achieved, theproblem of aligning the relatively small optical fibers with openings inthe connector, while at the same time manipulating the terminationarrangements, requires at least a high level of skill or training, andmakes field installation difficult.

SUMMARY OF THE INVENTION

It is accordingly a first objective the invention to provide a fiberoptic connector to which a fiber optic cable may be terminated withoutthe need for adhesives, and yet which provides improved stabilityrelative to conventional adhesiveless fiber optic connectors so as tominimize attenuation of optical signals at the fiber-to-fiber interface.

It is a second objective of the invention to provide a fiber opticconnector that uses a main body cast from suitable liquid metals,alloys, or polymers, and a collet arrangement which fits within the mainbody in place of adhesive or epoxy based glue to compress, swage, andadhesively bond a compressive material to the fiber and the main body soas to provide improved stability and minimization of attenuation ofoptical signals at the fiber-to-fiber interface.

It is a third objective of the invention to provide a fiber opticconnector to which a fiber optic cable can be terminated under fieldconditions by a person with minimal instruction or training.

It is a fourth objective of the invention to provide an ST multimodeadhesiveless connector which meets the above objectives of theinvention.

It is a fifth objective of the invention to provide apparatus forfacilitating termination of a fiber optic cable to an adhesiveless fiberoptic connector, so that termination of the fiber to the connector canbe performed by a field installer with minimal instruction.

It is a sixth objective of the invention to provide a method ofterminating a fiber optic cable to an adhesiveless fiber opticconnector, which provides improved stability and attenuation propertiesrelative to conventional adhesiveless connection methods, and which canbe performed by a field installer with minimal instruction.

These objectives are accomplished, according to a preferred embodimentof the invention, by providing an adhesiveless fiber optic connector inwhich an optical fiber, buffer, dielectric layer or strength member, andjacket of a fiber optic cable are secured in the connector by a colletmechanism having cable gripping fingers for initially gripping the fiberbuffer upon movement of the collet into a body of the connector, andwhich is subsequently secured to the buffer by crimping, the crimpingoperation also securing the jacket to the main body of the connector andthe main body of the connector to the collet, and by providing thecollet with keying tabs which cooperate with slots in the main body toinitially hold the collet in the connector and prevent rotation of thecollet, the key forming an interference fit upon pushing of the colletinto the connector, and the material of the collet being selected sothat when the collet is crimped against the buffer, the collet adheresto the main body and securely fixes the collet to the main body withoutthe need for addition of adhesive materials.

The objectives of the invention are also achieved, in accordance with apreferred embodiment of the invention, by providing apparatus forfacilitating termination of a fiber optic cable to an adhesivelessconnector which includes mechanisms for transporting a prepared cablealong a predetermined path towards a connector, for guiding an opticalfiber extending from the cable towards an appropriate opening in theconnector as the cable is moved by the transporting mechanism, forsecuring the cable buffer to the transporting mechanism duringtransport, and for releasing the cable and pushing the collet into theconnector upon positioning of the cable in the connector to retain thecollet in the connector for crimping.

By providing mechanisms for guiding the fiber and securing the cablebuffer to the transport mechanism, the apparatus of the preferredembodiment frees the installer from the task of manually guiding thefiber while at the same time attempting to manipulate thecable-to-connector securing features.

Finally, the objectives of the invention are achieved in accordance witha preferred embodiment of the invention, by providing a method ofterminating a fiber optic cable to a connector including the steps ofpreparing a cable by exposing the optical fiber, buffer and insulatingor strength layer, capturing the optical fiber within guiding means inthe form of pivotal jaws, securing the optical fiber to a transportingmechanism by means of the cable buffer, and moving the transportingmechanism so as to insert the cable into the connector body until thebuffer abuts a limit surface at one of the jaws or an equivalent stop,releasing the cable buffer from the transporting mechanism, causing thetransporting mechanism to continue to push on the collet until thecollet engages the cable buffer, and crimping the main body to thecollet, the collet to the buffer, the cable strength member to the mainbody, and a crimping ferrule to the cable jacket.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional side view of an assembled adhesiveless fiberoptic connector constructed in accordance with the principles of apreferred embodiment of the invention.

FIG. 2 is a cross-sectional side view of the main body of theadhesiveless fiber optic connector illustrated in FIG. 1.

FIG. 3 is an end view of the main body illustrated in FIG. 2.

FIG. 4 is a perspective view of a collet used in the adhesiveless fiberoptic connector of FIG. 1.

FIG. 5 is a perspective view of one of the two symmetrical members whichmake up the collet illustrated in FIG. 4.

FIG. 6 is a cross-sectional side view of the main body illustrated inFIGS. 2 and 3 and the collet illustrated in FIG. 4, after the collet hasbeen latched into the main body but prior to the beginning of cabletermination.

FIG. 7 is a cross-sectional side view of the main body and colletillustrated in FIG. 6, after pushing to the key limit.

FIG. 8 is a cross-sectional side view of the main body and colletillustrated in FIG. 6, after insertion of the collet into the main bodyduring termination but prior to crimping.

FIG. 9 is a perspective view of the collet illustrated in FIG. 4, aftercrimping.

FIG. 10 is a perspective view of an alignment block, transportmechanism, and release lever for a cable termination apparatusconstructed in accordance with the principles of a preferred embodimentof the invention.

FIG. 11 is a plan view of the alignment block illustrated in FIG. 10.

FIG. 12 is a perspective view of an optical fiber guiding mechanism forthe preferred cable termination apparatus.

FIGS. 13A-13C are front elevations of the optical fiber guidingmechanism illustrated in FIG. 12.

FIG. 14 is a side view of a portion of the optical fiber guidingmechanism illustrated in FIG. 12.

FIG. 15 is a perspective view of a mechanism for securing a fiber opticcable buffer to the transport mechanism of the preferred cabletermination apparatus.

FIGS. 16A and 16B are elevations of the buffer securing mechanismillustrated in FIG. 15.

FIG. 17 is a partially cross-sectional top view showing a crimpingmechanism of the preferred cable termination apparatus, and thetransport mechanism after a fiber optic cable has been transported intoa final position in a fiber optic connector.

FIG. 18 is a partially cross-sectional side view of the preferred cabletermination apparatus following transport of the cable to the positionshown in FIG. 17, including a crimping mechanism and fiber cutting andpolishing mechanism.

FIG. 19 is a perspective view of the crimping mechanism and the fibercutting and polishing mechanism illustrated in FIGS. 17 and 18.

FIG. 20 is a flowchart summarizing a cable termination method accordingto a preferred embodiment of the invention.

FIGS. 21A and 21B are plan view of a variation of the preferredembodiment of the invention which includes an alternative stop mechanismfor positively limiting movement of the preferred cable translatingmechanism.

FIG. 22 is a cross-sectional side view showing the connector holding andpositioning mechanism used in the preferred embodiment.

FIG. 23 is a front view of a portion of the connector holding andpositioning mechanism shown in FIG. 22.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a fully-assembled fiber optic connector constructedaccording to a preferred embodiment of the invention.

Many of the features of the connector illustrated in FIG. 1, which willbe described in more detail below, are conventional, including the useof a collet 17 which is inserted between a main body 7 of the connectorand the fiber buffer 3, and which includes means for gripping the bufferas the collet is pushed into the main body, the collet subsequentlybeing crimped to provide an adhesiveless means for securing the cablewithin the connector. However, the connector illustrated in FIG. 1includes at least two features which are not conventional, and whichoffer the advantages of retaining the collet in the main body before thebeginning of termination, of preventing rotation of the collet duringtermination, and of assisting in the securing process followingtermination. These features are the inclusion of slots 27 in main body7, illustrated in greater detail in FIGS. 2 and 3, and keys 21 on collet17, illustrated in greater detail in FIGS. 4-9. The keys 21 fit intoslots 27 to retain the collet 17 in the main body 7 and prevent rotationof the collet before and during initial insertion of the fiber into theconnector, are subsequently pushed partly out of the slots to create africtional lock between the collet and the main body before crimping,and finally facilitate the formation of a cohesive bond by cold adhesionbetween the main body and the connector following crimping. Although useof the collet of the preferred embodiment thus provides the advantagesof using an adhesive, positively preventing drift, those skilled in theart will appreciate that the connector may still be considered anadhesiveless connector since no separate adhesive is used, and becausethe steps of applying and drying an adhesive are eliminated from thetermination process.

As shown in FIG. 1, the fiber optic cable 1 to which the connector ofthe preferred embodiment is terminated is made up, as is conventional,of a glass fiber 2, a buffer 3 surrounding the fiber, a strength member4, and a jacket 5. The fiber is positioned within a central bore 6' ofan alignment ferrule 6, conventionally made of a ceramic material, andthe alignment ferrule is positioned in a main body 7 of the connector,although-it will be appreciated by those skilled in the art that thealignment ferrule could also be insert molded into the main body, oreven made of the same material as the main body and molded therewith, oralternatively the main body could be made of multiple members, one ofwhich fits inside the other to support the alignment ferrule, with thecollet (described below) fitting into the outer portion of the mainbody.

A coupling nut 10 provided with inner threads (not shown) and aninwardly extending flange 12 is mounted on the connector main body 7,and a coil spring 10' is positioned between a collar 11 at the front ofthe main body 7 and flange 12 to bias the connector body, and also thealignment ferrule, forwardly when the coupling nut is secured to amating connector so that the front surface of the alignment ferruleabuts against a corresponding surface of an alignment ferrule of themating connector. The coupling nut 10 is retained on the connector mainbody 7 before mating by a snap ring or c-clip 13 situated in a groove 14on the connector body, and the ferrule 6 is retained within theconnector main body by an interference fit and axially positioned by ashoulder 8 at the rear of the ferrule-receiving opening 24.

The cable is secured in the fiber optic connector by the above-mentionedcollet 17 and a crimp ferrule 18. In the position illustrated in FIG. 1,the glass fiber 2 of the cable has been inserted through the collet andcentral bore 6' of ferrule 6 so that is extends past the end of theferrule for subsequent cutting and polishing according to conventionalmethods. The fiber buffer 3, on the other hand, extends only partiallyinto a central passage 20 in collet 17, while the strength member 4 ofthe cable has been separated from the buffer and extends around theoutside of the collet.

The collet is held within the main body 7 by crimping the main bodydirectly to the collet, and in particular by applying crimping pressureagainst the main body in the area of keys 21, causing keys 21 to deformand adhere to the main body, while the strength member 4 of the cable issecured to the connector by crimping it between crimp ferrule 18 andcollet 17, and the jacket 5 of the cable is further secured by crimpingthe rear of the crimp ferrule 18 to form an inwardly extending grippingsection 17'.

In addition, cable gripping arms 22 extending to the rear of the collethave been cammed inwardly upon insertion of the collet to its finalposition relative main body so as to grip the fiber buffer 3, as will bedescribed in greater detail below, thus securing the fiber within theconnector and eliminating the possibility of drift which would lead tomisalignment of fibers after mating to a corresponding connector.Finally, a boot 23 is fitted over the crimp ferrule 18 to provide strainrelief for the cable 1.

As shown in greater detail in FIGS. 2 and 3, details of the connectormain body 7 include collar 11 for engaging the front end of coil spring10', a cylindrical bore 24 at the front of the main body for receivingthe ceramic fiber alignment ferrule 6, groove 14 for receivingnut-retaining c-clip 15, and tapered rear passage 25 for receiving acorrespondingly tapered front portion of collet 17. In addition, mainbody 7 features ribs 26 formed by crimping to provide improved retentionof the cable strength member following crimping, key slots 27 forcooperating with keys 21 to retain the collet in the connector prior totermination, as will be explained in greater detail below, and apolarization key 28 which is part of the standard ST connector designand cooperates with a corresponding key on a mating connector.

The connector main body 7 may be made from a material such as stainlesssteel or mild steel, or a polymeric material, including insert moldedmaterials, but a die cast alloy such as Zamac is preferred. Potentiallysuitable materials for the collet include liquid crystal polymers andother thermosets or epoxy resins containing fillers and additives asnecessary to provide high thermal, flow, and dimensional stability,including polyphenylene sulphides, polyethylethylketones, and otherpolymeric composites, all of which are within the scope of theinvention, but the preferred materials for the collet are resincopolyesters such as poly benzoate-napthoate or polynaphtoateaminophenoterephthalate. The latter materials are particularlypreferred because of their adhesion properties when subjected topressure from the main body during crimping, with the heavy zinc complexions in the Zamac material nf the main body actually adhering tooxidizing agents in the resin copolyester material by localized cohesivebonding.

Although the illustrated connector is an ST type connector, it will beappreciated by those skilled in the art that the principles of theillustrated collet may be adapted for use in connectors other than theillustrated connector, the outer housing of the connector and the fiberalignment ferrule being described herein for illustrative purposes only.

Collet 17 is illustrated in greater detail in FIGS. 4-9, and is made upof two symmetrical halves 30 and 31, each including a locating pin 32and an opening 33, a v-groove 34 for locating the glass fiber 2 strippedof its buffer 3, a larger groove 35 extending to the rear of groove 34including tapered entry portion 34' for locating the fiber buffer, afrustoconical intermediate passage 36 between grooves 34 and 35 forguiding a fiber into the groove 34, and the above-mentioned cablegripping arms 22 including surfaces 37 for gripping the cable buffer 3,with respective keys 21 being situated midway along opposite edges oftwo of the arms 22. A ramp surface 40 on the edge of each arm slopesoutwardly from the key 21 to the rear of the collet, and a shoulder 41extends between the ramp surface and a rear section 42 of the collet ina direction transverse to the collet axis.

The nose or front section 43 of collet 17 wedges into the surface oftapered intermediate section 25 of main body 7, while the opposite endof the collet, including ramp surfaces 40, engages the main body 6 uponpushing of the collet into the connector during cable termination, andcauses the arms 22 to flex inwardly and grip the buffer 3 of the cableas the collet is pushed further into the connector. The height andcompressibility of keys 21 is such that the keys 21 can compresssufficiently to pass into the slots 27 through the rear section of themain body 7 after the collet has been assembled by press fitting pins 32into openings 33, with the restoring force on keys 21 causing them toextend into the corresponding slots 27 upon passage through the rearsection such that the rear edges 46 of the keys 21 cooperate with therear edges 47 of slots 27 and the forward edges 48 of the keys cooperatewith the front edges 49 of the slots to retain the keys in the slots andthe collet within the connector body prior to termination. The positionof the keys in the slots permits the collet to conveniently be retainedin the main body so that the collet does not need to be handled duringtermination.

The functions of the keys 21 is illustrated in FIGS. 6-8. FIGS. 6 and 7respectively show the rearward and forward limits of key movement withinslot 27, before the collet is forced further into the main body in orderto grip the cable, while FIG. 8 shows the position of the collet afterthe front edge 48 of each key has been pushed past front edge 49 ofslots 27 and the collet is in its final position relative to the mainbody prior to crimping.

Before the beginning of termination, as shown in FIGS. 6 and 7, thecollet can shunt backwards and forwards over a short distance determinedby the difference in elongated lengths of the slot openings 27 and thelength of the keys 21, with movement of the collet being limited byengagement between edges 46 and 48 of the keys and edges 47 and 49 ofthe slots, thereby retaining the collet loosely in the connector andeliminating the need to for the installer to locate and handle thecollet. For an ST connector, an appropriate shunting distance would beon the order of 0.01". In addition, the collet is prevented fromrotation by engagement between the sides of the keys and the sides ofthe slots.

As the collet assembly is shunted forwards, the front face of the colletis positioned just inside the inner wall taper 25 formed in thecylindrical bore 24 of the connector body. Because the forward edges 48of the keys 21 are lower than the rear edges 46, and only slightlyhigher than the corresponding front edges 49 of slots 27, an increase inpressure at the rear of the collet following shunting of the key 21 tothe position shown in FIG. 7 at the front of the slot causes the keyedges 48 to deform and pass beneath the edges 49 of the slot. The topsurface 50 of the keys is slightly concave in shape to permit furtherinsertion of the collet into the main body until the height of the topsurface increases towards the rear of the keys, at which point, as shownin FIG. 8, an interference fit between the keys and the main body isachieved, and the gripping arms 22 extending towards the rear of thecollet have been cammed inwardly against the cable buffer 3 byengagement between tapered sections 40 and the inner surface at the rearof the main body.

In this position, the front edges of the v-grooves 34 in the colletcorrespondingly wrap around the edge of the glass fiber. Further forwardpressure causes the collet to guide and so limit the position of thefiber, with the friction fit of the collet v-groove around the barefiber limiting the forward position of the bare fiber and so determiningthe stop position for the front face of the collet assembly. The barefiber end extends through central bore 6' and protrudes from the frontface of the ferrule 6 inserted in the main body 7. A tool for providingthe necessary forward pressure against the back faces of the colletassembly can be used, as described below, although it will beappreciated that the collet may be pushed into the main body byapparatus other than the illustrated apparatus. After insertion to thelimit of forward movement, the collet assembly is secured by crimpingthe back of the main body as shown in FIG. 8 to form gated pair edges orribs 26 in the area indicated by reference numeral 52, and at the sametime deform the keys to cause them to adhere to the inner surface of themain body, as described above, and as illustrated in detail in FIG. 9.

The preferred fixture or apparatus for terminating fiber optic cable 1to the ST collar connector described above is shown in FIGS. 10-18.While other tools or methods could be used, the illustrated cabletermination apparatus is particularly advantageous because it can beused by an installer, with minimal training or instruction, under fieldconditions and with minimal installation time. The apparatus consists ingeneral of an alignment block 100, shown in FIGS. 10 and 11, a cabletranslating mechanism 102 supported in a groove 101 of the alignmentblock and also shown in FIG. 10, a jaw mechanism supported by thealignment block for guiding the bare fiber of the cable as it is movedby the cable translating mechanism, as shown in FIGS. 12-14, a fiberbuffer clamping mechanism which includes a main body 125 attached to thefront 126 of the translating mechanism 102 as shown in FIGS. 15, 16A,and 16B, a crimping mechanism 115 shown in FIGS. 17-19 and a fibercutting mechanism 117 shown in FIG. 18. FIG. 18 also gives an overallview of the entire apparatus, from the cable transporting mechanism tothe crimping and cutting mechanisms, all of which are fixed relative toa base or the bottom of a carrying case for convenient handling.Finally, FIGS. 19 and 22 also show a in detail an x-y translatingmechanism made up of blocks and guides 148, 148', 149, and 149', andstops 159-161, for moving the connector holder mechanism 116 between aninitial position suitable for loading the cable into the connector andperforming the initial crimping operation, and two additional crimpingpositions.

As shown in FIGS. 10 and 11, the alignment block 100 is formed by ametallic block having overall dimensions approximately those of a 2"cube. A long groove or slot 101 approximately 1/8" wide by 3.75" long iscut in the top surface of block 100 to accommodate a cable translatingmechanism 102 which is manually movable along an axis of the slot. Asmaller cable supporting slot 103 extends along the top of thetranslating mechanism 102 in the direction of movement. Translatingmechanism 102 is arranged to guide a fiber into a connector uponcoupling of the connector to a holder fixed relative to the alignmentblock, following clamping of the fiber buffer to the translatingmechanism by means of the clamping mechanism illustrated in FIGS. 15,16A, and 16B, as described in more detail below, while the fiber itselfis guided by the jaw mechanism illustrated in FIGS. 12-14, and alsodescribed in detail below.

Also attached to the alignment block 100 is a spring loaded rocker 106having an end 107 which in a first position extends into an enlargedportion 108 of slot 101 at the front of the alignment block to keep thetranslating mechanism 102 from falling into the enlarged portion 108,which is deeper than the remainder of the slot, and which when pushed toa second position after the cable translating mechanism has been movedto a forward position to project forwardly of the alignment block, exitsthe enlarged portion 108 to permit the cable translating mechanism to betilted into the slot and away from the axis of cable insertion.

Attached to the front of the cable translating mechanism 102 is a cableclamping mechanism 124, as illustrated in FIGS. 15, 16A, and 16B.Clamping mechanism 124 includes a buffer guide head 125 secured to aflange 126 at the front of the translating mechanism, a v-groove 127situated at the top of the head member for positioning the cable buffer3, and a buffer clamping lever 128 pivotally mounted on buffer guidehead 125 to secure the cable buffer during cable transport.

The alignment block also includes a jaw mechanism support 109 having aseat 110 for a jaw mechanism actuator wheel 111, a mounting hole forwheel 111, and mounting holes 112 for the individual jaws 113 and 114 ofthe jaw mechanism, which is illustrated in FIGS. 12-14. The jawmechanism support 109 extends forwardly of the cable translatingmechanism slot 101 so that when the jaws are mounted thereto and in theclosed position shown in FIG. 13A, the jaws are positioned apredetermined distance from the slot opening to define a forward limitfor manual movement the translating mechanism, further movement of thetranslating mechanism being permitted only after opening of the jaws tothe position shown in FIG. 13C.

Finally, the crimp mechanism 115, shown in FIGS. 17-19, a connectorholder 116 shown in FIG. 18 which preferably includes a keyway (notshown) for orienting the connector body relative to the alignment block,and a fiber cutting mechanism 117, also illustrated in FIGS. 18 and 19.

The purpose of jaws 113 and 114 is to support and guide the bare opticalfiber into the connector. The jaw mechanism, as shown in FIGS. 12-14,includes jaws 113 and 114, actuator wheel 111, pins 118 for engaging andseparating the jaws upon movement of the wheel 111, stops 119 forlimiting movement of the jaws, and a lever 121 for moving the actuatorwheel. Lower jaw 113 includes an alignment head v-groove 120 having amarking along its length to indicate initial placement of the opticalfiber 2. Upper jaw 114 is arranged to capture the optical fiber in thealignment head v-groove 120 and includes limit surface 122 whichcooperates with surface 123 on the lower jaw for limiting forwardmovement of the cable by engagement with the buffer 3 of the cableduring termination, as best shown in FIG. 17.

At the rear of the alignment block 100 is mounted a lever 104, shown inFIG. 18, having an end 105 which engages a downwardly depending rearsection 104' of cable translator 102 in a notch 105' below the slot tomove the cable translating mechanism forwardly within the slot underincreased pressure to the position shown in FIG. 17 after the cable hasalready been positioned in the connector, as will be described in moredetail below. Mounting holes 112' are included at the rear of thealignment block for attaching the mounting block 113 for lever 104.

The crimp mechanism 115, best shown in FIG. 19, includes at least threecrimp openings 136-138 formed by jaws 139 and 140, for respectivelycrimping collet 17, strength member 4, and jacket 5, as described above.To permit the respective crimping operations to be successivelyperformed while maintaining alignment between the jaws and the area tobe crimped, jaws 139 and 140 are slidable transversely to the axis ofthe connector to selectively bring the different crimp opening intoposition relative to the connector, and also are adjustable parallel tothe axis of the connector so as to provide the necessary alignment.Movement and adjustment of the crimp jaws can be provided by a manualactuator 141 and an actuator 142, actuator 142 having openings 143 intowhich can be inserted a tool 144 for providing the necessary leverage toobtain an effective crimp. In order to simplify the crimping process,fiducial marks 136', 137', 138' and 116' may be included on upper jaw140 and on an upper surface of a bulkhead of the connector holder toassist in aligning the respective crimp openings 136-138 during thecrimping process.

The connector holder mechanism 116 includes handle 147 which can bemanipulated to translate a first slide block 148 supported by guides 149and attached to an extension of bulkhead 150 of the holder mechanism,guides 149 being provided on a second slide block 148' also translatableby handle 147 relative to a guide or track 149' to form an x-ytranslation device. On one side of bulkhead 150, as best shown in FIG.22, is an adapter 151 to which the connector is attached, while theopposite side of bulkhead 150 includes ferrule stop 146 which preciselydefines the position of the ferrule relative to the cutting mechanism117. The manner in which ferrule stop 146 extends in front of thealignment ferrule of the connector is shown in FIG. 23.

The x-y translation device as shown in FIG. 19 cooperates with threestops 159-161 to position the connector relative to the crimp mechanism115 and the cable translation device in one of three positions P1, P2,and P3. Stop 159 is fixed and stops 160 and 161 are pivoted into place.Initially, the stops 160 and 161 are pivoted into a non-engagingposition and the handle 147 is slid towards the fixture front, at whichpoint the connector is attached to the holder. The handle is thenrotated counterclockwise to move the x-y translation mechanism againstthe fixed stop 160, and locked. Subsequent to the initial crimping, thehandle 147 is rotated clockwise to unlock it and moved away from thefixed stop 159, the second stop 160 is pivoted into position, the handle147 pushed forward to permit placement of the crimp ferrule 18 over theconnector main body, and then the handle is moved to position the x-ytranslation mechanism against stop 161 and the handle rotated into alocked position. Finally, subsequent to the second crimping operation,the handle is again rotated clockwise to unlock it, moved to clear thethird stop 161 so that it can be pivoted into place and the x-ytranslating mechanism moved up against the third stop, and rotated tolock the x-y translating mechanism into position.

The final mechanism including in the claimed apparatus is cuttingmechanism 117, depicted in FIGS. 18 and 19 as including a diamond knife135 of known construction which can be brought into position, after thefiber has been inserted into a connector and secured by crimping and bythe action of the collet, so as to cut the fiber and enable polishing orbuffing of the fiber and ferrule to form a smooth interface forengagement with a correspondingly prepared fiber and ferrule of a matingconnector, thus completing the preferred apparatus for facilitatingtermination of an optical fiber cable to an adhesiveless fiber opticconnector.

Although the back stop of the alignment guide head provides an adequatelimit stop for the translating mechanism, it may be preferable toinclude a separate stop mechanism, as illustrated in FIGS. 20A and 20B.The alternative stop mechanism is in the form of a spring-loaded stop130 situated at the top of alignment block 100 adjacent the groove 101,so that an extension 131 of the stop 130 extends into the path of twopins 132 and 133 on the translating mechanism 102. When the translatingmechanism is pushed forward so that the fiber has been guided into theconnector, extension 131 initially engages pin 132 to provide theinitial stopping point at which jaws 113 and 114 are released. The stop130 is then pulled back against the force of a bias spring 130' torelease pin 132 so that the translating mechanism can be moved forwardto as second position, at which pin 133 engages extension 131 and thebuffer guide head 125 is positioned at the back of the collet. The stop130 can then be pulled back again to permit further pushing of thecollet into the connector.

The preferred method of terminating a fiber optic cable to a connectorcan advantageously use the above-described fixture, but could also beaccomplished with other tools or possibly even by hand, and issummarized in the flowchart of FIG. 20.

The first step in terminating a cable according to the preferred method,generally designated by step 200, is to prepare the cable. Initially,the cable is cut to a desired length and the strain relief boot is slidonto the end of the cable. Then, using a template, the outer jacket isstripped to reveal a length of the strength member, typically made ofKevlar™. The strength member is folded back to expose the underlyingbuffer, which is marked and a portion of the buffer is stripped from thesignal-carrying glass fiber at the center of the cable, completingpreparation of the cable for termination.

The next step, designated generally by step 201, is carried out afterthe connector has been secured to connector holder 116 such that thelongitudinal axis of the connector is coincident with an axis of thelongitudinal groove in the cable transport member, by collet aligningkey 21 with a corresponding keying feature on the connector holder, andby securing the coupling nut 10 to a corresponding threaded portion ofthe connector holder. With the lever 104 in a disengaged position andcable translating mechanism 102 pushed back as far as possible in slot101 of the alignment block 100, the fiber guiding jaws 113 and 114 areinitially positioned as shown in FIG. 13A. The upper jaw 114 is thenopened as shown in FIG. 13B. At this time the prepared cable can bepositioned in groove 103 of the transport mechanism, with the glassfiber 2 being seated in the v-groove 120 of lower jaw 113 and manuallypositioned so that the end of the fiber is approximately 1 mm past amarking in the guide slot containing the v-groove.

Then, as indicated by step 202, with the fiber having been axiallypositioned for transport, the upper jaw 114 is lowered back to theposition shown in FIG. 13A and the fiber 2 is captured by the upper jaw114 so as to retain the fiber in the v-groove while permitting axialmovement of the fiber relative to the upper and lower jaws.

Step 203 is carried out after capturing the fiber 2 between jaws 113 and114, and while holding onto the cable jacket so as to ensure that thecable is properly seated in the transport mechanism slot 103, andinvolves securing the fiber buffer to the transport mechanism by closinglever 128 to capture the buffer in the buffer positioning slot 127 ofthe buffer guide head 125, at which time the cable is ready fortransport by moving the transport mechanism. If necessary to furthersecure the cable in the translating mechanism 102 for movement towardsthe connector held in fixture 116, the cable jacket 5 can also be heldby the thumb and forefinger of the hand moving the transport mechanism.

As the transport mechanism is pushed forward towards the closed upperand lower jaws 114 and 113, which it will be recalled are fixed to theguide block so that the jaws are a distance away from the alignmentblock, the fiber passes through and is guided by the jaws and into thecollet 17 of the connector, at which point the fiber is guided by thenarrowing passage in the nose of the collet to enter the alignmentferrule 6. Movement of the transport mechanism continues until the fiberbuffer 3 reaches the limit stop 123 extending from the upper jaw 114, oruntil the spring-loaded stop 130 of the variation shown in FIGS. 21A and21B has engaged pin stop 132, at which point the fiber has beenpartially inserted into the ferrule and is in the position shown in FIG.17.

Then, according to step 204, the lower and upper jaws 113 and 114 of thefiber termination apparatus are fully opened to the position shown inFIG. 13C by rotating the lever 121 counter-clockwise to permit furtherinsertion of the fiber into the alignment ferrule 6 and insertion of thebuffer into the collet. When the front of the transport mechanism abutsagainst the rear of the collet, or an equivalent stop, or the extension131 on spring-loaded stop 130 of the variation shown in FIGS. 21A and21B has engaged pin 133, the handhold on the cable can be released.

The step of finally positioning the cable in the connector, designatedgenerally by step 205, is accomplished by pushing on lever 104 onmounting block 100 to move the collet further into the connector,thereby causing engagement of the gripping fingers of the collet ontothe cable buffer, and forward movement of the keys 21 out of the slots27 to form an interference fit between the collet and the main body, atwhich point insertion is complete, lever 128 can be pivoted to unclampthe fiber.

Following release of the cable, the crimping mechanism 115 is positionedto secure the crimp ferrule 18 to collet 17, as well as to secure thestrength member 4 and jacket 5 as described above. This step isdesignated in FIG. 20 as step 206, and involves positioning of thecrimping mechanism in conjunction with manipulation of handle 147 andstops 159-161 in the manner described in more detail above. Prior toloading of the cable, the crimping mechanism has been positioned to asto place opening 136 over the rear of the connector so that opening 136is in a position to crimp the main body of the connector to the collet.Subsequently, handle 147 is released and manipulated to move permitplacement of the crimp ferrule 18 over the main body movement of themain body into a position where opening 137 of the crimping mechanismcan be placed over the crimp ferrule 18 to secure the strength member,and again manipulated to place the connector in a position where opening138 can be placed over the small diameter of the crimp sleeve andthereby secure the crimp sleeve to the cable jacket.

Finally, in step 207, after placing the boot 23 over the crimp ferruleto the position shown in FIG. 1, the connector is ready for cleaving ofthe excess fiber from the front end of the alignment ferrule 6 usingcutting mechanism 135. The connector can then be released from itsholder and lever 106 can be pushed to cause the translating mechanism102 to drop into enlarged portion 108 of slot 103 and thereby releasethe cable from the transport mechanism. Subsequently the connector maybe placed on a standard polishing fixture that accommodates theassembled connector. A plastic plate may also be placed on the flat ofthe fixture plate for rapid hand polishing, or a battery operatedpolishing wheel could be mounted in unison with the cutting tool.Finally, after polishing, a dust or safety cap (not shown) can be usedto cap the ferrule and protect the fiber interface prior to coupling toanother connector.

Having thus described various preferred embodiments of the invention,those skilled in the art will appreciate that variations andmodifications of the preferred embodiment may be made without departingfrom the scope of he invention. It is accordingly intended that theinvention not be limited by the above description or accompanyingdrawings, but that it be defined solely in accordance with the appendedclaims.

We claim:
 1. An adhesiveless fiber optic connector, comprising:aconnector main body; and a collet including a gripping device, saidgripping device being moved to a gripping position at which it grips anelement of a fiber optic cable when the collet is pushed to a forwardposition in the connector main body during termination of the cable tothe connector, and retention elements arranged to cooperate withretention features on the collet to loosely retain the collet in theconnector, wherein before said collet is pushed to said forward positionin the main body during termination of the cable to the connector, saidcollet is free to move within the connector main body without fallingout, and without causing said gripping device to move to said grippingposition.
 2. An adhesiveless fiber optic connector as claimed in claim1, wherein the gripping device comprises gripping fingers extending fromthe collet, the gripping fingers including cam surfaces arranged toengage cam surfaces on an inside the main body, engagement of therespective cam surfaces causing the gripping fingers to move towardseach other and grip a buffer of the cable as the collet is pushed intothe connector.
 3. An adhesiveless fiber optic connector as claimed inclaim 1, wherein the retention elements comprises keys extendingradially outward from said collet and said retention features compriseslots in said main body, said slots extending in a direction parallel toa direction of insertion of said collet into said main body.
 4. Anadhesiveless fiber optic connector as claimed in claim 3, wherein aheight of the keys is such that the keys are retained in the slot untila force is applied which causes front edges of the keys to deformsufficiently to pass front edges of the slot, and wherein said keyscontinue to move forward after exiting the slot in response to saidpressure to form an interference fit with the main body.
 5. Anadhesiveless fiber optic connector as claimed in claim 4, wherein saidkeys are further deformed by crimping pressure applied to a crimpferrule surrounding the main body, said crimping pressure causingcohesive bonding between a material of said collet and a material ofsaid main body.
 6. An adhesiveless fiber optic connector as claimed inclaim 5, wherein said material of said collet is a copolyester resin andsaid material of the main body is a zinc alloy.
 7. An adhesiveless fiberoptic connector as claimed in claim 5, wherein said material of the mainbody is a composite resin.
 8. An adhesiveless fiber optic connector asclaimed in claim 7, wherein said composite resin is a copolyesterpolymer.
 9. An adhesiveless fiber optic connector as claimed in claim 1,wherein said connector further includes a coupling nut surrounding saidmain body, a ferrule through which a bare fiber of the cable extends toa mating interface, and a coil spring for biasing the main body, andtherefore the ferrule, forwardly in a mating direction.
 10. Anadhesiveless fiber optic connector as claimed in claim 1, furthercomprising a crimp ferrule surrounding said main body, said crimpferrule being arranged to secure the main body to the collet and thestrength member to the collet, and to be crimped a jacket of the cable.11. An adhesiveless fiber optic connector, comprising:a main body; acollet including a gripping device for gripping an element of a fiberoptic cable as the collet is pushed to a forward position in the mainbody during termination of the cable to the connector, and deformableelements for causing the collet to adhere to the main body upondeformation caused by crimping after the collet is pushed to the forwardposition in the main body, said deformable elements also being arrangedto cooperate with retention features in the main body to loosely retainthe collet in the main body before the collet is pushed to the forwardpositions, wherein before said collet is pushed to said forward positionin the main body, said collet is free to move within the connector mainbody without falling out, and without causing said gripping device togrip said fiber optic cable element.